Different sized main jets on carbs

[TylerM]

I just pulled the carbs on my "new" 81 GS550L for the first time and found something odd. Upon taking off the main jets, I found that two of them were size 100, and two of them were size 97.5. The stock size jet seems to be 92.5, based on the charts I found here. The PO also had cheapo pod filters on it, which explains the larger jets, but why were there two different sizes?


I plan on going back to the stock airbox, and that means I'll need the stock size jets. Should I just buy a rebuild kit? Or is there a better way to get the stock jets?

[tkent02]

There's a better way. Z1 Enterprises. Some of the newer bikes with inadequate cooling fins and airflow used richer jets on the inboard cylinders, to kep them a little cooler. Maybe that's what your PO was doing.

The 550s had no such cooling problems.

[Guest]

I just pulled the carbs on my "new" 81 GS550L for the first time and found something odd. Upon taking off the main jets, I found that two of them were size 100, and two of them were size 97.5. The stock size jet seems to be 92.5, based on the charts I found here. The PO also had cheapo pod filters on it, which explains the larger jets, but why were there two different sizes?


I plan on going back to the stock airbox, and that means I'll need the stock size jets. Should I just buy a rebuild kit? Or is there a better way to get the stock jets?

Rebuild kits are expensive and you don't really need them. Here is what you will need. New orings, get these at Cycleorings.com has everything you need. Might go ahead and order some new bowl gaskets, sometimes you can reuse the old one sometimes you can't. Check the float needles if they are groove sometimes you can polish it out, if not, get the needles and seats. DEFINITELY reinstall the stock air box and go back to the stock jets. Keep in mind the factory made these bikes a bit on lean side to pass the emissions at that time. If you have the front rubber boots on the carbs, if they are hard and cracked, get new ones along with the clamps. If you do go back to the stock air box, probably need new rear boots as well and the clamps.

There are carb rebuild tutorials on BassCliffs website: http://members.dslextreme.com/users/bikecliff/
just follow these steps and are you are good to go. You should be getting a welcome soon that will list his website for ya.

Remember you have a 33 year old bike that needs 20 years of maintenance.

[jbthomp]

I got mine from www.jetsrus.com They have a great selection and they got to my house in 2 days.

[JMHJ]

I seem to remember a guy from here (renobruce) tearing into his '85 1150 that he bought new and finding different sized jets.

The 700 that we had for a year and a half or so had foam pod air filters (and a V&H 4-1), 40k+ miles and ran REALLY well. Whoever did it must've know how to set it up right.

[tkent02]

The 1150s came with the different sized ones I think.

[hillsy]

The 1150s came with the different sized ones I think.

Yes - 120 on the outer and 122.5 in the middle IIRC.

[bwringer]

If you really want to rip your hair out in handfuls, try encountering a set of jets some imbecile has drilled out...

There are also morons out there who have taken it upon themselves to "improve" the shape of the needles with sandpaper.

[Steve]

The 1150s came with the different sized ones I think.

Yes, they did, and so did the '83 and up 550s, the ones with the two-barrel carbs.

.

[tkent02]

I should have said the eight valve 550s had no such cooling problems.

Or I could have just said the eight valve GSes had no such cooling problems.

[JMHJ]

I seem to remember a guy from here (renobruce) tearing into his '85 1150 that he bought new and finding different sized jets.

The 700 that we had for a year and a half or so had foam pod air filters (and a V&H 4-1), 40k+ miles and ran REALLY well. Whoever did it must've know how to set it up right.

What happened to ol' bruce, btw? Seems like he was in financial straits some time back, and was gonna hafta sell that beautiful blue and white bike...